This invention relates to valves, and is particularly well-suited for use in tubeless tire valves of the type which either snap in place or are clamped in place on a wheel rim.
There is at present interest among tire manufactures to increase the working pressures of tubeless tires used for automobiles. Because of this interest, it is increasingly important that tire valves for tubeless tires be able to operate reliably at high working pressures.
European patent application No. 83 108 204 discloses one prior art tire valve. This tire valve includes a valve body which defines a through passageway and a constriction at an intermediate portion of the passageway. A valve pin is slideably positioned in the passageway and carries a sealing member positioned to bear against a sealing surface defined by the constriction to seal the passageway. The valve pin further defines a flange adjacent the sealing member, and this flange has an external diameter slightly larger than the minimum diameter of the passageway at the constriction such that the flange is sized to pass through the constriction without destruction of the pin or the valve body. This valve provides a high bursting pressure, significantly higher than the bursting pressure of conventional tire valves. Nevertheless, at extremely high working pressures the valve pin can be observed to move with respect to the valve body. Such valve pin movement may be a disadvantage in some applications, because it may create the appearance of unreliability. Of course, at a higher working pressure the valve will burst and allow the valve pin to be expelled out of the valve body.
One object of this invention is to provide a valve which can be adapted for use with tubeless tires, which seals in a perfectly reliable manner at unusually high working pressures, which is unusually inexpensive to manufacture, and which provides both reduced valve pin movement at high working pressures and an increased bursting pressure as compared with the valve described in the above-identified European patent application.